Houses need a concrete basement, joists bolted to rebar, piles sunk deep into clay or sandstone, solidly anchoring them to the ground. Otherwise, they leave; drift away.
People are careful now with their houses, keeping them in bondage to the earth, but in the early days before they were made fast to bedrock or cement, houses escaped.
Sometimes you see the empty pits of cellars, abandoned by the houses that once crouched over them like broody hens trying to persuade stone eggs to hatch.
Houses escaped when they got the chance, skidding along briskly on wooden runners, stalking sedately on scaly legs, floating on the foaming surge of a rising tide, driven by the wind.
If you look right at the horizon, you might see one sliding over the edge or slinking behind a clump of trees. The courageous ones rise toward the clouds on wings of flame.